Art kingpin Larry Gagosian’s upscale store at 988 Madison Ave., at 77th Street, has shut its doors after just two years in business. The 2,500-square-foot duplex space, near Gagosian’s gallery at 980 Madison Ave., sold publications, posters and lower-priced limited-edition pieces. The inventory — from framed art to furniture, skateboards and T-shirts — related to Gagosian shows and artists including Richard Prince, Jeff Koons, John Currin, Tom Friedman, Ellen Gallagher, Marc Newson, Tom Sachs and Franz West. The shuttered shop’s lower level was devoted to British artist Damien Hirst’s Other Criteria, which sold limited-edition books, posters and accessories. A worker at the store said that all its merchandise would shift to an online site. A Gagosian rep did not get back to us last night. It’s unclear why the space suddenly went dark. But when an art insider was asked if the closure might be for financial reasons, the source shot back, “Not with Larry, it isn’t.”